U.S. patent number 4,439,551 [Application Number 06/476,736] was granted by the patent office on 1984-03-27 for packaging foam polyurethane composition employing novel polyol blend.
This patent grant is currently assigned to Texaco, Inc.. Invention is credited to Michael E. Brennan, Michael Cuscurida, Ernest L. Yeakey.
United States Patent |
4,439,551 |
Yeakey , et al. |
March 27, 1984 |
Packaging foam polyurethane composition employing novel polyol
blend
Abstract
Economical, open-celled packaging foams of better quality than
foams from commercial aromatic polyester polyols may be prepared
with a novel polyol blend. The most important component in the
polyol blend is an aromatic polyester polyol made from dibasic acid
waste streams and recycled polyethylene terephthalate. This type of
polyol made from waste or recycled reactant streams is economical
to make and serves as an inexpensive substitute for a portion of
more expensive amino polyols normally used.
Inventors: |
Yeakey; Ernest L. (Austin,
TX), Cuscurida; Michael (Austin, TX), Brennan; Michael
E. (Austin, TX) |
Assignee: |
Texaco, Inc. (White Plains,
NY)
|
Family
ID: |
23893037 |
Appl.
No.: |
06/476,736 |
Filed: |
March 18, 1983 |
Current U.S.
Class: |
521/131;
252/182.25; 521/172; 560/92; 521/48.5; 528/308.1; 516/18;
516/DIG.7 |
Current CPC
Class: |
C08G
18/6655 (20130101); C08G 18/4213 (20130101); C08G
18/4216 (20130101); Y10S 516/07 (20130101); C08G
2110/0075 (20210101); C08G 2110/005 (20210101) |
Current International
Class: |
C08G
18/66 (20060101); C08G 18/00 (20060101); C08G
18/42 (20060101); C08G 018/14 () |
Field of
Search: |
;521/172,173,131,48.5
;528/308.1 ;560/92 ;252/182,357 |
References Cited
[Referenced By]
U.S. Patent Documents
|
|
|
3590070 |
June 1971 |
Martin et al. |
4048104 |
September 1977 |
Svoboda et al. |
4223068 |
September 1980 |
Carlstrom et al. |
|
Primary Examiner: Welsh; Maurice J.
Attorney, Agent or Firm: Park; Jack H. Priem; Kenneth R.
Mossman; David L.
Claims
We claim:
1. A method for making low density packaging polyurethane foam
comprising reacting in the presence of a tertiary amine catalyst of
polyurethane formation and a blowing agent, an organic
polyisocyanate and a polyol blend comprising
a. 10 to 25 wt.% of an aromatic polyester polyol having a hydroxyl
number of from 210 to 230 which is the reaction product from
(1) esterifying, in the absence of a catalyst, a residue from
dibasic acid manufacture which comprises one or more acids from the
group consisting of glutaric acid, succinic acid and adipic acid,
with an alkylene glycol to produce a polyester polyol intermediate,
and
(2) transesterifying, in the absence of a catalyst, recycled
polyethylene terephthalate with the polyester polyol intermediate
of the previous step,
b. 30 to 50 wt.% of a rigid amino polyol having a hydroxyl number
of from 440 to 540 which is based on sucrose or an aromatic amine
polyol,
c. 5 to 25 wt.% of an organic surfactant alcohol, and
d. 25 to 35 wt.% of a polyether triol having a molecular weight of
at least 4,500 and a primary hydroxyl content of greater than
75%.
2. The method of claim 1 in which the aromatic polyester polyol has
the following structure ##STR5## where x is an integer between 2
and 4, inclusive.
3. The method of claim 1 in which the rigid amino polyol is
prepared by reacting from 2 to 3 moles of an alkylene oxide with
one mole of the Mannich reaction product of a mole of phenol or
nonylphenol with one or two moles of diethanolamine and one or two
moles of formaldehyde.
4. The method of claim 1 in which the organic surfactant alcohol is
an alkylene oxide adduct of nonylphenol.
5. The method of claim 1 in which the blowing agent is
trichlorofluoromethane in a proportion of 25 to 50 parts by weight
based on 100 parts by weight of the polyol blend.
6. The method of claim 1 in which the density of the resulting
polyurethane packaging foam ranges from about 0.4 to 0.7 pounds per
cubic foot.
7. A polyol blend composition for lowdensity packaging foam
formulations comprising
a. 10 to 25 wt.% of an aromatic polyester polyol having a hydroxyl
number of from 210 to 230 which is the reaction product from
(1) esterifying, in the absence of a catalyst, a residue from
dibasic acid manufacture which comprises one or more acids from the
group consisting of glutaric acid, succinic acid and adipic acid,
with an alkylene glycol to produce a polyester polyol intermediate
and
(2) transesterifying, in the absence of a catalyst, recycled
polyethylene terephthalate with the polyester polyol intermediate
of the previous step,
b. 30 to 50 wt.% of a rigid amino polyol having a hydroxyl number
of from 440 to 540 which is based on sucrose or an aromatic amine
polyol,
c. 5 to 25 wt.% of an organic surfactant alcohol, and
d. 25 to 35 wt.% of a polyether triol having a molecular weight of
at least 4,500 and a primary hydroxyl content of greater than
75%.
8. The polyol blend composition of claim 7 in which the aromatic
polyester polyol has a structure of the following formula ##STR6##
where x is an integer from 2 to 4.
9. The polyol blend composition of claim 7 in which the rigid amino
polyol is prepared by reacting from 2 to 3 moles of an alkylene
oxide with one mole of the Mannich reaction product of a mole of
phenol or nonylphenol with one or two moles of diethanolamine and
one or two moles of formaldehyde.
10. The polyol blend composition of claim 7 in which the organic
surfactant alcohol is an alkylene oxide adduct of nonylphenol.
11. A low-density, open-celled packaging foam made by the process
comprising
reacting in the presence of a tertiary amine catalyst of
polyurethane formation and a blowing agent, an organic
polyisocyanate and a polyol blend comprising
a. 10 to 25 wt.% of an aromatic polyester polyol having a hydroxyl
number of from 210 to 230 which is the reaction product from
(1) esterifying, in the absence of a catalyst, a residue from
dibasic acid manufacture which comprises one or more acids from the
group consisting of glutaric acid, succinic acid and adipic acid,
with an alkylene glycol to produce a polyester polyol intermediate,
and
(2) transesterifying, in the absence of a catalyst, recycled
polyethylene terephthalate with the polyester polyol intermediate
of the previous step,
b. 30 to 50 wt.% of a rigid amino polyol having a hydroxyl number
of from 440 to 540 which is based on sucrose or an aromatic amine
polyol,
c. 5 to 25 wt.% of an organic surfactant alcohol, and
d. 25 to 35 wt.% of a polyether triol having a molecular weight of
at least 4,500 and a primary hydroxyl content of greater than
75%.
12. The foam of claim 11 in which the aromatic polyester polyol has
the following structure ##STR7## where x is an integer between 2
and 4, inclusive.
13. The foam of claim 11 in which the rigid amino polyol is
prepared by reacting from 2 to 3 moles of an alkylene oxide with
one mole of the Mannich reaction product of a mole of phenol or
nonylphenol with one or two moles of diethanolamine and one or two
moles of formaldehyde.
14. The foam of claim 11 in which the organic surfactant alcohol is
an ethylene oxide adduct of nonylphenol.
15. The foam of claim 11 in which the following components were
also present in the indicated proportions
a. 10 to 30 pbw of water based on 100 pbw of the polyol blend,
b. 25 to 50 pbw of a fluorocarbon based on 100 pbw of the polyol
blend,
c. 3 to 10 pbw of a tertiary amine catalyst based on 100 pbw of the
polyol blend, and
d. a 2.7 functionality polyisocyanate present in such a proportion
that the ratio of mole equivalents of isocyanate groups to mole
equivalents of hydroxyl groups ranges from 0.3 to 0.6.
16. The foam of claim 11 in which the blowing agent is
trichlorofluoromethane.
17. The foam of claim 11 in which the density of the resulting
packaging foam ranges from about 0.4 to 0.7 pounds per cubic foot.
Description
CROSS-REFERENCE TO RELATED APPLICATION
U.S. Pat. application Ser. No. 443,778 filed on Nov. 22, 1982
reveals aromatic polyols used in the novel polyol blend herein
which may be made from recycled polyethylene terephthalate, and
alkylene glycol and dibasic acid waste streams.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to polyol blends to be used in low density
packaging foams and more particularly relates to such blends and
foams which use an aromatic polyester polyol made from recycled
polyethylene terephthalate and alkylene glycol and dibasic acid
waste streams.
2. Description of Relevant Compounds and Methods in the Field
Open-celled, low density packaging foams are widely used for the
encapsulation or packaging of shock-sensitive objects. These foams
are generally made by mixing two preformulated components, commonly
called the A-component and the B-component. The A-component
typically contains the isocyanate compound that must be reacted
with the constituents of the B-component to form the packaging
foam. The B-component contains the balance of the foam ingredients;
namely, polyol, water, surfactant, fluorocarbon and amine catalyst.
A typical B-component will contain 10 to 30 parts by weight (pbw)
water, 15 to 40 pbw fluorocarbon and 100 pbw polyol, plus small
quantities of catalyst and surfactant.
U.S. Pat. No. 4,087,389 to Olin Corporation describes packaging
foam compositions prepared from a reaction mixture characterized by
high levels of water and an organic foaming agent, and a reaction
mixture NCO/OH index of from about 30 to about 60. The composition
employs a triol obtained by condensing one mole of glycerine first
with propylene oxide, then with ethylene oxide. Canadian Pat. No.
866,233 is another patent in this field that discloses how low
density, open-celled polyurea foams may be made by reacting
undistilled aromatic polyisocyanurates with water.
Another type of polyisocyanurate foam employs a polyol blend using
both amide diols and primary hydroxyl polyols to give a foam having
a large reaction exotherm, making it particularly suited to the
preparation of polyisocyanurate foam laminates, according to U.S.
Pat. No. 4,246,364.
As noted, one of the polyols used in the invention herein is an
aromatic polyester polyol made from scrap polyethylene
terephthalate (PET). Scrap PET is known to be incorporated into
polyurethanes. For example, U.S. Pat. No. 4,048,104 relates that
polyisocyanate prepolymers for use in polyurethane products may be
prepared by combining an organic polyisocyanate with polyols which
are the hydroxylterminated digestion products of waste polyalkylene
terephthalate polymers and organic polyols. A polyol ingredient
which is the digestion product of polyalkylene terephthalate
residues or scraps digested with organic polyols is also described
in U.S. Pat. No. 4,223,068. Another case where terephthalic acid
residues are employed is outlined in U.S. Pat. No. 4,246,365 where
polyurethanes are made from polyesters containing at least two
hydroxyl groups and terephthalic acid residues.
Also relevant to this plyol portion of the invention is U.S. Pat.
No. 4,237,238. In this patent, a polyol mixture is prepared by the
transesterification of a residue from the manufacture of dimethyl
terephthalate with a glycol, which is then used to produce
polyisocyanurate foams having a combination of a high degree of
fire resistance with low smoke evolution, low foam friability and
high compressive strength. The preparation of such a polyol mixture
(from ethylene glycol and dimethyl terephthalate esterified oxidate
residue) is described in U.S. Pat. No. 3,647,759. J. M. Hughes and
John Clinton, in the Proceedings of the SPI 25th Annual Urethane
Division Technical Conference, Scottsdale, Arizona (October, 1979),
describe other foams prepared from the polyols of U.S. Pat. No.
3,647,759. However, one of the problems with the polyols of U.S.
Pat. No. 3,647,759 is that they are not very compatible with
trichlorofluoromethane, the gas commonly used as a blowing
agent.
Another of the polyols used in the invention herein is made as
described in U.S. Pat. No. 4,137,265, incorporated by reference
herein.
SUMMARY OF THE INVENTION
The invention concerns a method for making low density packaging
polyurethane foam by reacting in the presence of a tertiary amine
catalyst and a blowing agent, an organic polyisocyanate and a
polyol blend containing 10 to 25 weight percent of an aromatic
polyester polyol. The aromatic polyester polyol has a hydroxyl
number of from 210 to 230 and is made by esterifying, in the
absence of a catalyst, a dibasic acid waste stream with an alkylene
glycol, the reaction product of which is transesterified with
recycled polyethylene terephthalate.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Typically, a single polyol is used to react with the polyisocyanate
to give a low-density packaging foam. However, in this invention a
blend of polyols and alcohols (known here as surfactants) are found
to be useful. Instead of using a single polyol, which may be
expensive, part of the blend is made up of polyols made from
residues and scraps. This partial replacement of expensive polyols
with inexpensive polyols makes the foams of this invention more
economical. Surprisingly, good packaging foams are obtained even
though some cheaper polyols are employed.
Aromatic Polyester Polyols
The novel aromatic polyester polyol mixtures are made by using a
recycled polyethylene terephthalate (PET). This may be any scrap
residue from old polyethylene terephthalate which contains
compounds which have the moiety ##STR1##
Generally, the scrap or recycled polyethylene terephthalate may be
in any particulate form. A frequently seen form is fragmentized
soft drink bottles which appear as clear or colored chips.
Polyethylene terephthalate film can also be recycled. Any chopping
or pulverizing process which produces small bits of solid PET from
the larger, waste recycled article would be appropriate to produce
scrap PET useful herein. Sometimes the scrap PET is mixed with a
solvent to make a kind of slurry. While scrap PET slurry could be
used in making these polyols, the recycled PET chips without the
solvent is also useful.
The polyester polyol with which the polyethylene terephthalate
scrap is reacted is produced by the esterification of a residue of
dibasic acid manufacture, as noted before. Dibasic acids are those
acids which have two displaceable hydrogen atoms. Examples of such
acids are succinic, glutaric and adipic acid. Especially preferred
are the residues from adipic acid which contain portions of each of
the three acids listed above. It is necessary that the acids be
dibasic so that polymer chains can be formed upon reaction with the
glycol. These materials may also include waste dicarboxylic
acids.
Preferably, the alkylene glycol has the formula ##STR2## where R is
hydrogen or lower alkyl of one to four carbon atoms and n is from 1
to 3. Glycols which meet this definition are ethylene glycol,
propylene glycol (1, 2-propylene glycol), diethylene glycol (DEG),
dipropylene glycol, and triethylene glycol (TEG), among others. The
glycol may be a residue or flash-separated glycol.
The polyester polyol which results from the reaction of the dibasic
acid residue and an alkylene glycol may be a diester diol. Such a
diol may be defined by the formula ##STR3## where x is 2 to 4.
The proportions of the reactants should be such as to give a
resulting mixture of aromatic polyester polyols which have an
average OH (hydroxyl) number within the desired range of about 100
to 400. The saponification number of the scrap polyethylene
terephthalate (a measure of transesterification sites) should be
considered in selecting proportions, if obtainable. One PET unit
has a molecular weight of 192.2. Preferably the approximate mole
ratio of scrap polyethylene terephthalate to dibasic acid to
alkylene glycol may be about 1:1:2. These proportions could vary 5%
in either direction. What actually forms the "polyol" is a mixture
of polyols having ester functions, even though the mixture is
sometimes a singular "polyol".
Generally, both reactions need heat between ambient and about
300.degree. C. to proceed. Preferably, the temperature for both
steps should be between 140.degree. and 220.degree. C. Unlike some
prior art processes, both steps are non-catalytic. The pressure can
be atmospheric, subatmospheric or autogenous. The polyol should
have a hydroxyl number in the range of 100 to 400, with an
especially preferred hydroxyl number range of 125 to 300. For the
purposes of this invention, the hydroxyl number should range from
about 210 to 230.
The structure of these aromatic polyester polyols has been
identified as follows: ##STR4## where x is an integer of from 2 to
4. The mixture that results from the process described has an
average value of x of around 3.
Rigid Amino Polyols
The rigid amino polyols useful herein are called "rigid" because
they are used primarily for rigid foams. These polyols are the more
expensive polyols used herein and the goal is to diminish their
proportion by replacing them with polyols such as those described
in the previous section.
The rigid amino polyols are produced by propoxylating or
ethoxylating a Mannich condensate. The Mannich reaction by which
the intermediate Mannich condensates are produced is generally the
reaction of phenols, formaldehyde and amines. More specifically, it
is a well-known reaction wherein an active hydrogen compound is
reacted with formaldehyde and a primary or secondary amine to
produce a substituted aminomethyl derivative of the active hydrogen
starting material. The Mannich reaction products used in preparing
the compounds of our present invention are prepared by premixing
one mole of the phenol or nonylphenol with one or two moles of the
diethanolamine and then slowly adding the requisite quantity of
formaldehyde at a temperature below the temperature of Novolak
formation. The ortho and para positions of these phenolic compounds
are sufficiently reactive to enter into the Mannich reaction. At
the end of the formaldehyde addition, the reaction mixture is
slowly heated with agitation to a temperature of at least about
50.degree. C., such as a temperature within the range of about
80.degree. C. to about 150.degree. C., for a period of time
sufficient to reduce the formaldehyde content to at most about 1
wt.%. This will require normally from about two to about four hours
reaction time at the elevated temperature.
The formaldehyde may be employed in any of its conventional forms,
such as aqueous formalin solution,an inhibited methanol-containing
solution, paraformaldehyde or trioxane.
At the end of the reaction, water is stripped from the reaction
mixture. The resulting crude Mannich reaction product may, without
further purification, be condensed with an alkylene oxide in the
manner hereinafter described, although it is preferably first
purged with nitrogen at reduced pressure. If desired, the reaction
product may be separated into specific components or fractions, but
products obtained by reacting the entire Mannich reaction product
with an appropriate quantity of alkylene oxide are included in the
definition of these rigid amino polyols.
The alkylene oxide used in further condensation is preferably
ethylene oxide, propylene oxide, butylene oxide or a mixture of
oxides. The condensation with alkylene oxide is carried out simply
by introducing the alkylene oxide, preferably under pressure, into
a vessel containing the Mannich reaction product. No added catalyst
is needed since the basic nitrogen in this product provides
sufficient catalytic activity to promote the reaction. Temperatures
between about 30.degree. and 200.degree. C. may be employed but the
preferred temperatures are in the range of about 90.degree. to
120.degree. C. Under these conditions the phenolic hydroxyl group
reacts first with one mole of the propylene oxide after which the
remaining one or two moles reacts with the alcoholic hydroxyls to
form hydroxypropoxyethyl groups. The final condensation products
are purified from unreacted and partially reacted materials by
vacuum stripping and are obtained as clear amber to brown liquids
having hydroxyl numbers in the range of 440 to 550 and viscosities
between about 15,000 and 45,000 centipoises at 25.degree. C.
U.S. Pat. Nos. 3,297,597 and 4,137,265 to Texaco Development
Corporation describe in detail the preparation of a number of these
nitrogen-containing Mannich polyols, and the disclosures of those
patents are incorporated by reference herein. The commercial
products made under these patents by Texaco Chemical Company are
known as THANOL.RTM. R-350-X and THANOL R-650-X polyols. The
preferred hydroxyl number for these rigid amino polyols is in the
range from about 440-540.
Organic Surfactant Alcohols
The organic surfactants used as part of the polyol blend are
actually alkylene oxide adducts of monofunctional alcohols. Simply,
an alkylene oxide such as ethylene oxide is added to an alcohol,
preferably containing an aromatic group such as nonylphenol. The
result is a long surfactant molecule with an alcoholic group on one
end and an aryl group on the other. These alcoholic surfactants are
made by well-known methods in the art which will further be
described in the next section.
Polyether Polyols
The last constituent of the overall polyol found particularly
useful in preparing rigid polyurethane packaging foams is a
polyether polyol having a hydroxyl number of 20-80. Usually the
polyether polyol comprises 0-95 percent by weight of the total
polyol combination weight. Preferred polyether polyols of this type
are the reaction products of a polyfunctional active hydrogen
initiator and propylene oxide, ethylene oxide or mixed propylene
oxide and ethylene oxide. The polyfunctional active hydrogen
initiator most preferably has a functionality of 2-8.
A wide variety of initiators may be alkoxylated to form useful
polyether polyols. Thus, for example, polyfunctional amines and
alcohols of the following type may be alkoxylated:
monoethanolamine, diethanolamine, triethanolamine, ethylene glycol,
polyethylene glycol, propylene glycol, polypropylene glycol,
glycerine, sorbitol, trimethylolpropane, sucrose and alpha-methyl
glucoside. Triol initiators are preferred.
Such above amines or alcohols may be reacted with an alkylene oxide
such as ethylene oxide, propylene oxide, or mixed ethylene oxide
and propylene oxide using techniques known to those skilled in the
art. Thus, for example, the reaction of alkylene oxide with
initiators of this type is set forth in U.S. Pat. Nos. 2,948,757
and 3,000,963. Essentially such alkoxylations are carried out in
the presence of a basic catalyst at a temperature sufficient to
sustain the reaction. The hydroxyl number which is desired for the
finished polyol would determine the amount of alkylene oxide used
to react with the initiator. As noted above, the polyether polyols
useful here have a hydroxyl number ranging from about 20 to about
80. The reaction mixture is then neutralized and water and excess
reactants are stripped from the polyol. The polyether polyol may be
prepared by reacting the initiator with propylene oxide or ethylene
oxide, or by reacting the initiator first with propylene oxide
followed by ethylene oxide or vice versa in one or more sequences
to give a so-called block polymer chain or by reacting the
initiator at once with propylene oxide and ethylene oxide mixture
to achieve a random distribution of such alkylene oxides.
Preferably, the last polyol is a triol having a molecular weight of
at least 4,500 and a primary hydroxyl content of greater than
75%.
The Polyol Blend
The novel polyol blend of this invention is made up of the four
types of polyols discussed previously. The polyols should be mixed
in the following proportions: from about 10 to 25 wt.% of an
aromatic polyester polyol, from about 30 to 50 wt.% of a rigid
amino polyol, from about 5 to 25 wt.% of an organic surfactant and
from about 25 to 35 wt.% of a polyether triol.
Polyurethane Packaging Foams
Preferably, the ingredients will be proportioned so as to provide
from about 0.3 to about 0.6 mole equivalents of isocyanate groups
per mole equivalent of hydroxyl groups provided by the polyol
blend. However, for the shock absorbing foams of this invention we
have found that the mole equivalents of isocyanate to hydroxyl
groups can be as low as 0.4.
It is within the scope of the present invention to utilize an
extraneously added inert blowing agent such as a gas or
gas-producing material. For example, halogenated low-boiling
hydrocarbons, such as trichloromonofluoromethane and methylene
chloride or carbon dioxide, nitrogen, etc., may be used. The inert
blowing agent reduces the amount of excess isocyanate and water
that is required in preparing flexible urethane foam. For a rigid
foam, the use of water is often avoided and the extraneous blowing
agent is used exclusively. Selection of the proper blowing agent is
well within the knowledge of those skilled in the art. See for
example U.S. Pat. No. 3,072,082. The polyol blend of this invention
is quite compatible with fluorocarbon blowing agents unlike some of
the prior art polyols made from DMT residues. For this invention,
it is preferred that the water content range from 10 to 30 parts by
weight (pbw) per 100 pbw of polyol blend. It is further preferred
that the proportion of fluorocarbon is 25 to 50 pbw based on 100
pbw of polyol blend.
The catalysts of this invention may be preferably a tertiary amine
or a mixture of amine catalysts. Tertiary amines include
trialkylamines (e.g. trimethylamine, triethylamine), heterocyclic
amines, such as N-alkylmorpholines (e.g., N-methylmorpholine,
N-ethylmorpholine, etc.), 1,4-dimethylpiperazine,
triethylenediamine, etc., and aliphatic polyamines, such as
N,N,N'N'-tetramethyl-1,3-butanediamine. Suitable commercial
catalysts include THANCAT.RTM. DD, THANCAT DPA and THANCAT TD-33
catalysts, among others, made by Texaco Chemical Company, The
preferred proportion of catalyst is 3 to 10 pbw per 100 pbw of the
polyol blend components.
Conventional formulation ingredients are also employed such as, for
example, foam stabilizers, also known as silicone oils or
emulsifiers. The foam stabilizer may be an organic silane or
siloxane. For example, compounds may be used having the
formula:
wherein R is an alkyl group containing from 1 to 4 carbon atoms; n
is an integer of from 4 to 8; m is an integer of from 20 to 40; and
the oxyalkylene groups are derived from propylene oxide and
ethylene oxide. See, for example, U.S. Pat. No. 3,194,773.
The isocyanate used in the A-component may be any aromatic
polyisocyanate. Typical aromatic polyisocyanates include
m-phenylene diisocyanate, p-phenylene diisocyanate, polymethylene
polyphenylisocyanate, 2,4-toluene diisocyanate, bitolylene
diisocyanate, naphthalene-1,4-diisocyanate,
xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate,
bis(4-isocyanatophenyl)methane, bis(3-methyl-4-isocyanatophenyl)
methane, and 4,4'diphenylpropane diisocyanate.
Greatly preferred aromatic polyisocyanates used in the practice of
the invention are methylene-bridged polyphenyl polyisocyanate
mixtures which have a functionality of from about 2 to about 4.
These latter isocyanate compounds are generally produced by the
phosgenation of corresponding methylene bridged polyphenyl
polyamines, which are conventionally produced by the reaction of
formaldehyde and primary aromatic amines, such as aniline, in the
presence of hydrochloric acid and/or other acidic catalysts. Known
processes for preparing polyamines and corresponding
methylene-bridged polyphenyl polyisocyanates therefrom are
described in the literature and in many patents, for example, U.S.
Pat. Nos. 2,683,730; 2,950,263; 3,012,008; 3,344,162 and
3,362,979.
Most preferred methylene-bridged polyphenyl polyisocyanate mixtures
used here contain about 20 to about 100 weight percent methylene
diphenyldiisocyanate isomers, with the remainder being
polymethylene polyphenyl polyisocyanates having higher
functionalities and higher molecular weight. Typical of these are
polyphenyl polyisocyanate mixtures containing about 20 to 100
weight percent methylene diphenyldiisocyanate isomers, of which 20
to about 95 weight percent thereof is the 4,4'-isomer with the
remainder being polymethylene polyphenyl polyisocyanates of higher
molecular weight and functionality that have an average
functionality of from about 2.1 to about 3.5. Preferably, the
functionality is about 2.7. These isocyanate mixtures are known,
commercially available materials and can be prepared by the process
described in U.S. Pat. No. 3,362,979, issued Jan. 9, 1968 to Floyd
E. Bentley.
The polyurethane packaging foams prepared here can be made in one
step by reacting all the ingredients together at once (one-shot
process) or the foams can be made by the so-called
"quasi-prepolymer method." In accordance with this method, a
portion of the polyol component is reacted in the absence of a
catalyst with the polyisocyanate component in proportion so as to
provide from about 20 percent to about 40 percent of free
isocyanato groups in the reaction product, based on the polyol. To
prepare foam, the remaining portion of the polyol is added and the
two components are allowed to react in the presence of a catalyst
and other appropriate additives such as blowing agents, foam
stabilizing agents, fire retardants, etc. The blowing agent, the
foam stabilizing agent, etc., may be added to either the prepolymer
or remaining polyol, or both, prior to the mixing of the component,
whereby at the end of the reaction a polyurethane foam is provided.
The foregoing methods are known to those skilled in the art, as
evidenced by the following publication: DuPont Foam Bulletin,
"Evaluation of Some Polyols in One-Shot Resilient Foams", Mar. 22,
1960. Other methods for making a suitable packaging foam are
described in U.S. Pat. No. 4,087,389, and that disclosure is
incorporated by reference herein.
The low-density, open-celled packaging foams of this invention
should have a density of 0.4 to 0.7 pounds per cubic foot (pcf).
These foams can be prepared at temperatures ranging from 25.degree.
to 60.degree. C.
The invention will be illustrated further with respect to the
following specific examples, which are given by way of illustration
and not given as limitations on the scope of this invention.
The polyol extenders of this invention (the aromatic polyester
polyols) will be compared with some commercial polyol extenders.
Hercules, Inc., Wilmington, Del., sells dimethyl terephthalate
(DMT) residues under the tradename of TERATE.RTM. 101. Hercules
also sells TERATE 200 series resins which are DMT resins modified
with a glycol as seen in U.S. Pat. Nos. 4,237,238 and 3,647,759.
The TERATE 200 series resins are useful as polyol extenders.
Similar DMT residues having a different composition but still
containing the aromatic esters and acids are also sold by DuPont
and others. Freeman Chemical Company produces a polyol extender
known as CHEMPOL.RTM. 30-2150 which has a hydroxyl number of about
210. It is the reaction product of recycled PET, diethylene glycol
and pure dimethyl glutarate, which is quite expensive. See U.S.
Pat. Nos. 4,223,068 and 4,048,104 to Freeman Chemical Co.
EXAMPLE I
This example will illustrate the use of the aromatic polyester
polyol of this invention in the preparation of low density
packaging foams. It will further show the improved foams which can
be made through use of this polyol extender as compared to a
competitive prior art polyol.
______________________________________ A B
______________________________________ Formulation, pbw THANOL
.RTM. R-510.sup.1 22.5 -- TERATE .COPYRGT. 203.sup.2 -- 22.5 THANOL
R-650-X.sup.3 22.5 22.5 THANOL SF-5505.sup.4 45.0 45.0 SUFONIC
.RTM. N-120.sup.5 10.0 10.0 Water 20.0 20.0 Fluorocarbon
R-11b.sup.6 35.0 35.0 Y-6690 Silicone.sup.7 2.0 2.0 THANCAT .RTM.
DPA.sup.8 5.0 5.0 MONDUR MR.sup.9 140.5 140.5 Details of
Preparation Cream time, seconds 12 12 Rise time, seconds 58 Foam
near collapse Gel time, seconds 60 at 20-25 sec., con- tinued to
rise Properties Density, pcf 0.54 Unable to measure Foam appearance
Fine Large coarse cells smooth cells
______________________________________ .sup.1 Aromatic polyester
polyol of this invention .sup.2 Competitive prior art polyol from
Hercules .sup.3 Aromatic amino polyol from Texaco Chemical Co.
(hydroxyl no. 460-480) .sup.4 5500 molecular weight high reactivity
polyol from Texaco Chemical Co. .sup.5 Twelve mole ethylene oxide
adduct of nonylphenol; Texaco Chemical Co. .sup.6
Trichlorofluoromethane blowing agent .sup.7 Silicone surfactant;
Union Carbide Chemical Corp. .sup.8 Two mole propylene oxide adduct
of dimethylaminopropylamine; Texac Chemical Co. .sup.9 2.7
functionality polymeric isocyanate; Mobay Chemical Co.
EXAMPLE II
This example will further illustrate the use of the aromatic
polyester polyol of this invention in the preparation of low
density packaging foams. It will further show that foams made using
the THANOL R-510 polyol have finer smoother cells than those made
using the prior art TERATE 203 polyol.
______________________________________ C D
______________________________________ Formulation, pbw THANOL
R-510 15 -- THANOL R-650-X 35 35 TERATE 203 -- 15 THANOL SF-5505
28.6 28.6 SURFONIC N-120 21.4 21.4 Water 20.0 20.0 Fluorocarbon
R-11b 35.0 35.0 Y-6690 Silicone 2.0 2.0 THANCAT DPA 5.0 5.0 MONDUR
MR 140.5 140.5 Details of Preparation Cream time, seconds 12 12
Rise time, seconds 55 42 Gel time, seconds 57 45 Properties
Density, pcf 0.56 0.57 Cell structure Smooth Coarse Cells per inch
50 35 ______________________________________
It may be readily seen from the examples that the polyol mixtures
of this invention work much better in the role of polyol extenders
than do commercially available materials. Many modifications may be
made in the polyol mixtures of this invention and their method of
production without departing from the spirit and scope of the
invention which is defined only in the appended claims. For
example, one skilled in the art could adjust the temperature,
pressure, proportions and modes of additions to provide polyol
blends that gives foams with optimal properties.
* * * * *